Background. Using implantable cardioverter-defibrillators in treatment of malignant ventricular arrhythmias revealed new complications specific to this therapy. Inappropriate therapy, arrhythmic storm and device related proarrhythmia belong to the most significant complications. The authors describe specific complications in a group of ICD patients, analyze their etiology and prognostic value. There are some recommendations for the management of specific complications. Methods and Results. 138 consecutive patients underwent ICD implantation between 1994-2001. Median follow-up was 47,35 months.Average left ventricular ejection fractionwas 38±14%and 71%of patients suffered from coronary artery disease. From the total of 2490 arrhythmic episodes 1490 were evaluated in detail. 253 episodes (17 %) were classified as inappropriate therapy. The most common etiology of inappropriate therapy was atrial fibrillation with rapid ventricular response (68%), atrial flutter (13%) and sinus tachycardia (11%). After the therapeutic intervention, 65 % of them remained free of inappropriate therapy. There were 38 arrhythmic storms in 19 patients as another serious complication. Conclusions. All the observed arrhythmic episodes were ventricular tachycardias (p<0.04). Patients with arrhythmic storm in history had significantly lower survival (p<0,05). The risk factors of cardiac nonsudden death were:a ge >66 years, left ventricular ejection fraction <35 % and arrhythmic storm history. The authors present recommendations for the treatment of the most common specific ICD complications.

        Key words: implantable cardioverter-defibrillators, inappropriate therapy, arrhythmic storm, proarrhythmia.